In large part because of Karl's influence, by the late 1970s, a number of painters were working out of doors in the Plein-Air Pastel tradition that artists like Theodore Lukits and William Louis Otte (1871–1957) had established in the 1920s. Professional career About the time Karl finished his academic studies with Theodore Lukits he began to exhibit his work professionally. He sold his first works to the veteran Los Angeles dealer Howard Morseburg (b. 1924), a relationship that began because of the dealer's long friendship with Thedore Lukits. These early. less mature works were done in oil, "worked up" from his pastel studies. They were brightly colored paintings depicting vivid sunrises and sunsets, broadly painted with little detail. According to Morseburg, because of the intense colors, the paintings did not sell well and after working with Karl for a number of months, the business relationship faded. Karl also began to work with Doug Jones, another veteran dealer who had the Jones Gallery in La Jolla, California. Jones encouraged Karl and purchased and sold a number of his paintings including both figurative and landscape works in oil and pastel. Both Morseburg and Jones have cited Karl's eccentricity and unreliability as an impediment to the development of his artistic career in the 1980s. Karl began working with Trailside Galeries in Scottsdale, Arizona, a large western gallery, in the mid-1980s, but because of his infrequent visits to Arizona, they were never able to sell his work steadily. It was not until the early 1990s, when he began working with Jeffrey Morseburg, Howard Morseburg's son, that his work began to be exhibited and sold steadily. While he seldom sold his pastel studies early in his professional career, by the mid-1990s, his dealer convinced him that his most personally revealing works were the ones done from nature and that the revival of interest in California Impressionism meant that there was a much greater appreciation for Plein-Air paintings. Morseburg began to market and advertise the works of a number of "Contemporary Plein-Air Painters" with Karl's works advertised and shown along with those of Peter Seitz Adams, Tim Solliday and the aging landscape painter Richard Rackus (b. 1922). Morseburg Galleries also hosted a number of large pastel exhibitions with Karl's work featured prominently. It was from these pastel exhibitions that the collector Sean Sullivan began his collection of pastels of the western American landscape that would later